Only barrel lengths offered in standard production:
5” field (light barrel only)
5.5” heavy barrel
5.5” light barrel (performance center model only)
7” (around 1978 and on)
7 3/8” (7” with a 3/8” extension for mounting the muzzle brake) Made from 1957 till about 1978.

There were variations (5.5” with extendable front sight) and later production came with drilled and tapped barrels. Also different sight options.

Jim